1. Technical Field
The present disclosure relates to digital control circuitry and, more particularly, to a system and method for verifying the operating frequency of digital control circuitry.
2. Discussion of Related Art
Many electrical systems, such as electrosurgical systems, employ digital control circuitry which drive time critical functions. The control circuitry could include, but is not limited to, microcontrollers, digital signal processors (DSPs) and field-programmable gate arrays (FPGAs). Typically, the digital control circuitry is clocked off of a single oscillator circuit. In the case of an oscillator circuit malfunction, the control circuitry may operate at an incorrect or undersirable frequency, which may be problematic. A few examples of systems which rely on accurate clock rate for effective operation include digital power supplies, RF inverters and ultrasonic inverters.
In the example of a digital power supply, the control circuitry provides PWM signals which are used to turn power mosfets on and off. Timing of these switching events is important. Not only could a shift in frequency result in loss of efficiency, but could also cause shoot-through or magnetic saturation, resulting in possible circuit failure.
Similar issues exist for inverter circuits, such as push-pull, full bridge or half bridge. Other concerns include clinical effectiveness and possible EMC violations if the output frequency drifts.
In a system that is space constrained, it would be desirable to have the ability for the control circuitry to confirm its own operating frequency, without complex external circuitry, prior to power output. In doing so, system confidence would be high prior to power generation and output knowing the output is within the system's operating frequency limits.